Application of zeolite

[Application] Zeolite is widely used in petrochemical, soil improvement, sewage treatment, metallurgy, medicine, atomic energy industry and light industry, and the building materials industry is the main application field of zeolite
.

In the field of sewage treatment, the zeolite can be used to remove ammonia, phosphorus, fluorine, arsenic, metal ions, organic pollutants, radioactive substances

① The natural zeolite has poor fluoride removal effect in the treatment of fluorine-containing sewage, and the modification treatment can make it have a strong fluorine removal ability
.

Hao Peiliang et al.

Table 4-2 Comparison of 15 kinds of fluoride removal agents

②The use of zeolite to remove ammonia nitrogen in wastewater treatment wastewater containing ammonia nitrogen has been extensively studied at home and abroad.
It is mainly believed that the mechanism of zeolite removal of ammonia nitrogen is adsorption of non-ionic ammonia and ion exchange with ionic ammonia.
The adsorption of non-ionic ammonia is dominant
.

The reason is that ammonia is a polar molecule, and the surface of zeolite is negatively charged, so it has a strong adsorption effect on ammonia

JorgensenT.
C.
et al.
studied the removal effect of clinoptilolite in the presence of organic matter in wastewater from ammonia nitrogen
.

Studies have shown that, compared with traditional biological methods to remove ammonia nitrogen and organic matter in wastewater, clinoptilolite treatment can better withstand shock loads and have a wider operating temperature range

Through research, Junichi Minato et al.
found that the modified zeolite prepared with a 3mol/L NaOH solution at 100°C has the highest adsorption capacity for ammonia nitrogen
.

Li Zhong et al.

③Removal of metal ions in wastewater Oukis.
K.
et al.
studied the effect of zeolite in removing heavy metal ions
.

In wastewater containing heavy metal ions, the selectivity order of clinoptilolite to heavy metal ions is Pb ²⁺ >Cu ²⁺ >Cd ²⁺ >Zn ²⁺ >Cr ³⁺ >Ni ²⁺

Liang Fengjiao et al.
used the homemade HDTMA fly ash zeolite as the adsorbent to conduct an experimental study on the adsorption of chromate
.

The influence of various factors such as the input amount of adsorbent, pH value of wastewater, adsorption temperature and adsorption time on the removal rate of Cr(VI) was discussed

Yuan Mingliang and others used a chemical co-precipitation method to combine natural zeolite with adsorption characteristics and magnetic iron oxide particles to prepare a magnetic zeolite composite with adsorption characteristics
.

Compared with sodium-type zeolite, the structure of magnetic zeolite does not change significantly, but the specific surface area increases from 25.

④Removal of organic pollutants The adsorption capacity of zeolite for organics mainly depends on the polarity and size of organic molecules
.
Organic molecules containing polar groups can strongly adsorb on the surface of zeolite and are easily adsorbed
.
By modifying natural zeolite, the adsorption effect of phenols and benzene organics can be improved
.

Saeid Razee et al.
studied the effect of zeolite in removing aromatic compounds
.
Adsorption of clinoptilolite on aniline, phenol , 4-methylaniline , 4-amino acid, 2-amino acid, 4-nitrophenol, 2-nitrophenol, 2-methyl-4-nitrophenol under the condition of 4h exposure The rate is 45%～64%, and the adsorption effect of zeolite is improved to 65%～74% after cyclodextrin (CD), especially a-CD modification
.

Lin Qiong et al.
used template-free hydrothermal synthesis and seed induced hydrothermal synthesis to prepare ZSM-5 zeolite, and used it for the adsorption of methyl tert-butyl ether (MTBE).
The study found that ZSM- 5 The adsorption capacity of zeolite for MTBE decreases with the increase of its dosage, and there is an obvious solid concentration effect; the adsorption system reaches the adsorption equilibrium slowly, indicating that the diffusion of MTBE in the micropores of ZSM-5 zeolite affects the adsorption equilibrium The zeolite is easy to regenerate, and has good regeneration adsorption performance for the treatment of MTBE solution with an initial mass concentration of 200-1000μg/L
.

Li Xiaohong et al.
synthesized cationized β-cyclodextrin (CCD) with 3-cyclodextrin and 2,3-epoxypropyltrimethylammonium chloride under alkaline conditions, and used it to modify zeolite to obtain cyclodextrin.
Dextrin modified zeolite (CDMZ)
.
The effect of CCD synthesis conditions on the adsorption of p-nitrophenol by CDMZ was studied
.
The results showed that under the synthesis conditions that the ratio of 2,3-epoxypropyltrimethylammonium chloride and β-cyclodextrin was 7:1 and the solution pH=13, the CDMZ pair obtained from the synthesized CCD-modified zeolite The adsorption capacity of p-nitrophenol is the best
.
At the same time, the effects of activation treatment before zeolite modification, initial concentration of CCD modified zeolite and modification time on the adsorption of p-nitrophenol by CDMZ were studied
.
Experiments show that activating zeolite with NaCl solution before modification can help improve the adsorption performance of CDMZ; when the initial concentration and modification time of CCD-modified zeolite are 15g/L (calculated as β-cyclodextrin) and 8h, respectively, The obtained CDMZ has an adsorption capacity of 263.
7μg/g for p-nitrophenol (120mg/L)
.

⑤Removal of radioactive substances Faghihian H et al.
studied the effect of natural clinoptilolite and its sodium salt form in different producing areas on the removal of Cs ⁺ and Sr ²⁺ in wastewater, and established and discussed its ion exchange adsorption isotherm
.
The results show that the low Si/Al ratio is beneficial to the removal of cations, and the sodium salt form is more effective than the unactivated zeolite
.
In sodium zeolite, the ion exchange equilibrium fraction of Cs ⁺ is 0.
32 eq/dm ³ , and the ion exchange equilibrium fraction of Sr ²⁺ is 0.
68 eq/dm ³
.

Related links: Preparation examples of zeolite molecular sieve from fly ash